Light microscope, resolution and magnification

Magnification = The number of times greater an image is than the object.

Resolution = The ability to distinguish 2 separate points as distinct from each other.

In a LIGHT MICROSCOPE, light passes from bulb under the stage, through a condenser lens, then through the specimen. Beam of light is focused through the objective lens then through the eyepiece lens.

Magnification of a light microscope = x1500. Resolution = 200nm.

Light microscopes do not have high resolution and so cannot give DETAILED information about internal cell structure.

STAINING: Chemicals that bind to chemicals or on the specimen. They allow the specimen to be seen and provide contrast. Some stains bind to specific cell structures e..g Acetic orcein stains DNA dark red and gentian violet stains bacterial cell walls.

SECTIONING: Specimens are embedded in WAX. Thin sections are then cut without distorting the structure of the specimen which is especially useful for making sections of soft tissue e.g. the brain.